Summary of Work: Functional imaging techniques are being used to characterize brain activation patterns in normal subjects and individuals with neurological disorders affecting affecting human communication. Brain activation patterns characterized using PET, fMRI or other brain mapping techniques may be used to characterize phenotypic presentation and neurological consequences of communication disorders. PET scans are performed on the GE Advance and Scanditronix PC2048-15B tomographs using the H215O method. Data are analyzed using Statistical Parametric Mapping software and newer covariance techniques developed in the section. fMRI studies are performed on 1.5 and 4Tesla instruments. Functional images are acquired using echoplanar and newer spin-tagging methods. Data are analyzed using IDL, SPM, fMRIap (NIMH) software and newer covariance techniques developed in the section. PET studies in individuals with developmental stuttering demonstrated hemispheric lateralization patterns that differed from those observed in control subjects, providing a model for the pathophysiology of this disorder. These studies were published in Brain, 120: 761-784. PET studies in normal subjects during sleep and wakefulness demonstrated unique patterns of cerebral activity associated with each of the individual sleep stages. These studies were published in Brain 120: 1173-1197. Further analyses of sleep-wake PET data have been submitted for publication. Functional MRI studies in deaf and hearing individuals demonstrated similar left hemisphere, but distinct right hemisphere, recruitment for English and American Sign Language. These studies are in press in the Proceedings of the National Academy of Sciences and in review in Nature. PET studies in normal volunteers demonstrated unique cerebral activation patterns associated with motor and linguistic elements of speech and significant differences for propositional vs. automatic speech. PET studies in persons fluent in both English and American Sign Language (ASL) demonstrated a robust left hemispheric lateralization for both spoken and signed language; intrahemispheric differences were detected however that appeared to reflect both linguistic and motor-expressive differences between English and ASL. PET studies in patients with spasmodic dysphonia demonstrated altered patterns of activity in motor and premotor cortices and basal ganglia that suggest a pathophysiological model for motor dysfunction in this disorder. Results of these studies are being prepared for publication. Novel analytic methods for neuroimaging have been developed by members of the section. A paper describing the use of singular value decomposition for analysis of PET data is currently in preparation. fMRI and PET studies in Parkinson's Disease are continuing.